1. Field of the Invention
The present invention relates to an inkjet recording method and to an inkjet recording apparatus suitable for rapidly recording a high quality image by an inkjet method.
2. Description of the Related Art
Inkjet methods of ejecting ink in the form of liquid droplets from an ink ejecting port has been used in various kinds of printers for the reasons of compactness and reduced costs, the ability to form an image without contacting a recording medium, and the like. These inkjet methods include a piezo inkjet method utilizing deformation of piezoelectric elements to eject ink and a thermal inkjet method utilizing the boiling phenomenon of ink caused by thermal energy to eject ink in droplets, which methods have the characteristics of high resolution and high-speed printability.
Improvements of speed and image quality are currently important objectives for when printing is carried out by ejecting ink droplets onto a plain paper sheet or a non-water-absorbing recording medium made of plastics or the like by use of an inkjet printer.
Inkjet recording is a method of ejecting ink droplets according to image data to form a line or an image on a recording medium with the liquid droplets. However, there have been problems in practical use, particularly in the case of recording on the above described non-liquid-absorbing recording medium, namely, for example, bleeding of an image easily occurs, or mixing of adjacent ink droplets occurs on the recording medium to inhibit formation of a sharply defined image, when the drying or permeation of the liquid droplets into the recording medium after being ejected takes some time. When the liquid droplets mix with each other, ejected adjacent liquid droplets coalesce with each other to move from the positions at which they have impacted the recording medium, thereby causing unevenness in line width when forming fine lines or unevenness in color when forming a colored area, or the like. Further, since the degree of occurrence of unevenness in line width or color unevenness in a colored area varies depending on ink absorbability and the wettability of the surface of the recording medium, there has also been a problem that different images are formed between different types of recording media, even though the same ink is used under the same ejection conditions.
As a method of suppressing image bleeding or nonuniformity of line width, a method exists of promoting fixation of liquid droplets. For example, methods of using two-liquid type inks having reactivity and allowing them to react with each other on a recording medium to achieve an imaging quality with high definition, such as a method of recording with ink containing an anionic dye after application of a liquid containing a basic polymer onto a medium (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 63-60783), or a method of applying ink containing an anionic compound and a coloring material after application of a liquid composition containing a cationic substance onto a medium (for example, refer to JP-A No. 8-174997) have been disclosed.
An inkjet recording method has also been proposed in which an ultraviolet-curable ink is used as the ink, and the ejected ink dots on a recording medium are irradiated with an ultraviolet ray in conformity with the timing of ejection, then the dots are pre-cured to be thickened to such an extent that the adjacent dots do not mix with each other, and thereafter the dots are further irradiated with an ultraviolet ray to complete curing (for example, refer to JP-A No. 2004-42548).
Further, a method has been proposed that improves visibility, reduces bleeding of color ink and suppresses the problem such as variation in the obtained images formed on different types of recording media, by applying a radiation curable white ink to form a uniform undercoating layer onto a transparent or a translucent non-absorbing recording medium, then curing or thickening the layer by irradiating with a radiation ray, and thereafter recording with a radiation curable color ink (for example, refer to JP-A Nos. 2003-145745 and 2004-42525). There has also been proposed a method in which a substantially transparent active ray-curable ink is applied by an inkjet head onto a recording medium in place of the radiation curable white ink (for example, refer to JP-A No. 2005-96254).